The present invention relates to a paper detection device for a printer.
For instance, a printer where printing on both cut sheets and continuous form are available needs to draw back a loaded continuous form from a printing area before printing on a cut sheet or to draw out a cut sheet at a paper jam treatment.
A detection sensor published on Japanese Utility Model Publication No. Hei. 3-43015 has a sheet end detection lever formed by an angled bar that may withdraw from a sheet feed passage when a print sheet is fed in either direction.
The angled detection lever of Hei. No. 3-43015, however, inaccurately detects paper because the timing of the paper detection depends upon the movement of the angled lever, which in turn depends upon the thickness of the paper and the rigidity of the lever. Thus, decreasing the thickness of the paper and increasing the rigidity of the lever decreases the likelihood of accurate paper detection, as the lever is less likely to move when paper is fed past the lever.
The present invention concerns such a problem as described above and thus the object of the invention is to provide a new paper detection device which performs accurate paper detection without impeding paper when it is fed in the sheet-feed direction or in the reverse-sheet-feed direction.
According to an aspect to the present invention, there is provided a paper detection device for a printer including: a support member; a main lever pivotably mounted on the support member, wherein the main lever has a self-resetability to an upright position and is pivotable only in a sheet-feed direction; an auxiliary lever pivotably mounted on the main lever that includes a free end that protrudes into a sheet passage, wherein the auxiliary lever has a self-resetability to an upright position, is pivotable with respect to the main lever only in a reverse-sheet-feed direction, and moves the main lever in the sheet-feed direction when the free end thereof is urged to the sheet-feed direction, but does not move the main lever in a reverse sheet feed direction when the free end of the auxiliary lever is urged in a reverse sheet feed direction.